Experimental Investigation of Rotational, Pumping, Magnetic Pumping and Toroidal Asymmetry Modes in a Toroidal Electron Plasma

Electron plasma is confined with a purely toroidal magnetic field in the Lawrence Non-Neutral Torus II ($R_{0} = $18 cm, \textit{a} $\sim$ 2 cm), for times ($\sim$ 1 s) that are much longer than any of the dynamical timescales of the system. The experiment can be operated as a variable-length partial torus or a full torus trap. The damping rate for the $m=$1 diocotron mode in a partial torus trap is found to depend on the equilibrium position (major radius) and on magnetic field (150 G -- 550 G). We report on efforts to explain these results in terms of rotational and magnetic pumping effects using 3D (Poisson-Boltzmann) equilibria calculations. Novel full torus asymmetry modes are examined with multiple separatrices and a new charge tomography is developed to infer charge density from image charge measurements on the conducting boundary.